The Crazy Thing That Makes You More Susceptible to Running Injuries

If you run, you know all too well that sports-related injuries are just part of the territory—about 60 percent of runners report getting injured in the past year. And that number can creep up to as high as 80 percent, depending on things such as what surface you're running on, the average time spent running, and exercise history or experience. This is according to a study published in the BMJ and it's not just scrapes, bruises, or black toenails we're talking about. Runners reported all kinds of overuse injuries in their legs and feet. And although knee injuries were the top complaint, many people suffered sprains, shin splints, plantar fasciitis, and the dreaded stress fractures.

If you love running, you aren't going to just stop lacing up to avoid getting hurt. But you'll want to learn some useful tips to prevent common running injuries, as well as what you might be doing to increase your risk. Well, the latest research found one crazy factor that's setting you up for pain in the future. You ready for this? It's running while female.

Research by Ohio State University found that underweight women with a BMI of 19 or under are at a much higher risk of being injured while running, and more specifically for getting stress fractures. Those two factors—gender and weight—each affect your running in different ways, according to Brian Schulz, M.D., orthopedic surgeon and sports medicine specialist at Kerlan-Jobe Orthopaedic Clinic in Los Angeles. "Stress fractures are one of the most common injuries we see in runners in general, but they do seem to happen more frequently in our female patients," he says.

Why? Simply put: female anatomy. Estrogen affects bone metabolism, and relaxin—a hormone that increases in pregnancy—loosens ligaments, especially as you age, says Dr. Schulz. Women also have smaller heart size than male runners, lower blood pressure, smaller lungs, and a lower VO2 max, which means hard exercise takes a bigger toll on women's bodies than it does on men's. (Just so we're clear, this does not mean women are not as strong, inside and out, as men.) As you age, that risk to your bones only increases, because as estrogen levels drop, your risk for osteoporosis and fractures increases, he adds.

There's also the "Q-angle," or the varied angle from your hip to your knee. Women have a naturally larger Q-angle than men, thanks to wider hips, which puts more stress on their joints, particularly the knees. And the more stress on your joints, the more likely you are to get injured, which may explain why women report more hip and knee pain after running, adds Dr. Schulz. "Because of wider hips, women's knees are more vulnerable to high-impact activities including running," says Steve Toms, head of personal training for Lifetime Fitness and corrective exercise specialist, in 9 Ways Being a Woman Affects Your Workout.

When it comes to weight, running to lose weight and running at a normal weight is generally fine for your body. But if you become underweight (a BMI of 19 or less), that can increase your risk of stress fractures, according to the Ohio State study. When you're underweight you don't have enough muscle mass and your bones end up absorbing all the shock, the researchers said in a press release.

So, great—you're a lean, healthy-weight woman who loves to run. Now what? Fortunately, there are some simple things you can do to lessen your risk of stress fracture and other running injuries.

One of the best things you can do is make sure your vitamin D levels are in the normal range, as this level is critical to bone health, says Dr. Schulz. Also, keeping your weight within a healthy range for your height will help, as being overweight or underweight can increase your risks. Of course, your BMI isn't the final word when it comes to good health, and it's more important to find your happy weight—the weight your body feels and works best at. Dr. Schulz also recommends running on soft surfaces when possible—say, the treadmill instead of concrete sidewalks—wearing shoes that fit properly (duh!), and not logging too many strides too quickly. A general rule of thumb is to up your mileage by no more than 10 percent per week.

Follow these tips and you'll be kicking butt in races (include passing plenty of men!) for years to come.